I don't think FFG rushes thing too much.
Look at the date Descent 2.0 was announced, that was nearly one year ago.
1e expansions were put out at a rate of roughly one per year (more for the ACs), and they still managed to make a mess.
If production takes 6-12 month you can suppose this expansion is already done and they already started working on the next one.
I know it might not be that great to skip community feedback at all, but it's just the way business works.
I don't really care if FFG considers community feedback, as long as the product they put out is decent quality.
For the record, when I say "decent quality" I don't mean it needs to be perfect in every respect. But I would appreciate if new rules were written with regard for past content, so they can be integrated seamlessly. I would appreciate if double-sided tiles did NOT print two different things that are required in the same quest on OPPOSITE SIDES OF THE SAME TILE. And I would appreciate if new heroes and monsters were roughly level in terms of overall power, so that the choice of which hero to play isn't reduced to a small set of "obvious" choices.
All of these things were problems in Descent 1e, by the end. All of them, IMHO, a result of cranking out expansions too quickly and without taking the time to think things through.
If they would start development of the new expansion now, we would have to wait way longer until we get new stuff.
I've said this before and I'll say it again: I'm cool with waiting longer for a product that is well thought out and well balanced, through and through.
Seeing a new expansion within a year of the base game's release worries me. I'm not saying it's guaranteed to be crap (I continue to hold out hope for the exact opposite.) However, it is an unfortunate fact that FFG has a reputation for lots of rules gaps that need to be addressed in FAQs. In the last couple years they've had two or three releases that were actually unplayable because components were printed incorrectly. So, the fact that they appear to be increasing the speed of their releases (at least superficially) is worrying to me.
It has already been suggested (by myself and others) that the base game may have been finished development a long time ago and held back by production/delivery issues. It was certainly announced far in advance of its eventual deployment. Hopefully this expansion has been in development for a while behind the scenes. If FFG has any sort of official comment on that suggestion, I would be very interested to see it (however, I'm not going to hold my breath.)
I'm as excited as the next guy for more Terrinoth content. I love Descent (1e, and 2e from what I've read of it.) I think FFG makes great games in general, but if that excitement ends up crumbling to ashes when I see a laundry list of errors in the product I just paid good money for, that's discouraging, to say the least.